The versatility of tractors and other like equipment is provided by front and rear hitching arrangements for mounting farm implements and other earth-working tools on the tractor. In this fashion, a single tractor unit may be adapted for use to perform a wide variety of soil preparation and cultivation operations. With soil cultivating implements having power-driven mechanisms, the hydraulic system of the tractor may be used for supplying pressurized hydraulic fluid to a hydraulic drive motor on the implement.
One type of soil cultivator which is adapted for mounting at the rear of a tractor is a power driven rotary cultivator or tiller. This type of cultivator typically includes a transversely extending housing adapted for mounting on a tractor hitch, and which rotatably supports a tined cultivator shaft. A drive mechanism operatively connects the cultivator shaft with a suitable power source. While some arrangements include power transmission members mechanically connecting the implement drive mechanism with a drive shaft or the like on the tractor, others include a self-contained source of mechanical power, such as a hydraulic motor, which may be supplied with pressurized hydraulic fluid from the hydraulic system of the tractor for operation of the cultivator. These latter types of arrangements are particularly convenient in that attachment and detachment of the cultivator to and from the tractor is simplified, with the power hook-up for the cultivator being easily accomplished by connection of suitable hydraulic fluid lines.
One drawback to the design of some rotary cultivators is the location of the drive mechanism for rotation of the cultivation shaft near the middle of the shaft. The arrangement of the drive mechanism in this manner prevents the inclusion of tines at the central portion of the shaft. The result of this configuration is usually the existence of a so-called "dead furrow" in the middle of the area tilled by the cultivator. Rotary cultivators which include a shaft drive mechanism disposed at one end of the cultivation shaft obviate this problem and provide a relatively smooth, continuous area of more uniform soil cultivation.
Because rotary cultivators are usually adapted to operate and cultivate soil at certain selected depths, the operation of the cultivator should provide for uniform penetration of the cultivator tines. This is an important consideration for cultivation of seedbeds since the depth of cultivation greatly influences the growing environment of seedlings. During use, some rotary cultivators may tend to "tobaggon" or "ride up" on the soil under certain conditions, thus resulting in undesired lack of uniformity of the depth of cultivation.
Another operational consideration of rotary cultivators relates to the torque input of the tined cultivator shaft. The torque requirements of the shaft differ considerably depending upon soil conditions and the speed of forward movement of the cultivator. In view of this, an arrangement for altering the torque characteristics of the cultivator shaft enhances versatility of the unit.
A further aspect of rotary cultivators design which affects operation is the width of the path of soil which the cultivator tills on a single pass. While a relatively wide path permits the operator of the cultivator to till a given area with fewer number of passes, a relatively wide machine may be unsuited for cultivation where clearance is limited. Thus, a rotary cultivator having an arrangement for selective shortening or lengthening of the rotary cultivation shaft to vary the width of the path of cultivation provides enhanced flexibility and versatility.
In view of these design considerations, a rotary cultivation arrangement which includes features for enhancing proper soil penetration, varying torque characteristics of the cultivation shaft, and altering the width of cultivation would clearly represent a more versatile and flexible unit.